As xerographic copiers and printers of all kinds increase in speed or decrease in paper path length to achieve smaller equipment footprints, heat provided to imaged sheets by fusing methods has significantly less time to dissipate prior to stacking. This results in an excess amount of heat stored in each copy sheet as it is delivered to a stacker or finisher. When these printed sheets are stacked, the combination of excess heat and pressure of the stack weight can fuse the two face to face images together. In the duplex mode, if the stack is left undisturbed, allowing the copy sheets to cool in the stack, the toner on the simplex side of one sheet can stick to the toner on the duplex side of the next sheet, thus fusing the sheets together. Obviously, it is difficult to subsequently separate these sheets, particularly in off-line finishing devices.
The following disclosure may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 3,901,591 issued to Sakae Mitsumasu is directed to a mechanism for cooling photosensitive materials in an electrophotographic copying machine that includes a cooling means for blowing a first air stream onto the surface of a photosensitive material and an air directing means for producing a second air stream through a thermal fixing device with the second air stream operating to draw the first air stream into and through the fixing device. A ventilator collects and discharges the air stream produced by the cooling means and the air directing means out of the copying machine after passing through the fixing device.
The above reference cited herein is incorporated by reference for its teaching.
Accordingly, although known apparatus and processes are suitable for their intended purposes, a need remains for an apparatus that can cool copy sheets before they enter a stacking or output tray.